判斷點是否在任意多邊形內(nèi)(java)
Java代碼
- import java.util.ArrayList;
- public class Test {
- public static void main(String[] args) {
- double px = 113.0253;
- double py = 23.98049;
- ArrayList<Double> polygonXA = new ArrayList<Double>();
- ArrayList<Double> polygonYA = new ArrayList<Double>();
- polygonXA.add(113.0253);
- polygonXA.add(113.4121);
- polygonXA.add(113.37109);
- polygonXA.add(113.02148);
- // 113.18359,23.8496
- // 113.0253,23.98049 113.4121,23.9687 113.37109,2.73828
- // 113.02148,23.7539C
- polygonYA.add(23.98049);
- polygonYA.add(23.9687);
- polygonYA.add(23.73828);
- polygonYA.add(23.7539);
- Test test = new Test();
- System.out.println(test.isPointInPolygon(px, py, polygonXA, polygonYA));
- }
- public boolean isPointInPolygon(double px, double py,
- ArrayList<Double> polygonXA, ArrayList<Double> polygonYA) {
- boolean isInside = false;
- double ESP = 1e-9;
- int count = 0;
- double linePoint1x;
- double linePoint1y;
- double linePoint2x = 180;
- double linePoint2y;
- linePoint1x = px;
- linePoint1y = py;
- linePoint2y = py;
- for (int i = 0; i < polygonXA.size() - 1; i++) {
- double cx1 = polygonXA.get(i);
- double cy1 = polygonYA.get(i);
- double cx2 = polygonXA.get(i + 1);
- double cy2 = polygonYA.get(i + 1);
- if (isPointOnLine(px, py, cx1, cy1, cx2, cy2)) {
- return true;
- }
- if (Math.abs(cy2 - cy1) < ESP) {
- continue;
- }
- if (isPointOnLine(cx1, cy1, linePoint1x, linePoint1y, linePoint2x,
- linePoint2y)) {
- if (cy1 > cy2)
- count++;
- } else if (isPointOnLine(cx2, cy2, linePoint1x, linePoint1y,
- linePoint2x, linePoint2y)) {
- if (cy2 > cy1)
- count++;
- } else if (isIntersect(cx1, cy1, cx2, cy2, linePoint1x,
- linePoint1y, linePoint2x, linePoint2y)) {
- count++;
- }
- }
- if (count % 2 == 1) {
- isInside = true;
- }
- return isInside;
- }
- public double Multiply(double px0, double py0, double px1, double py1,
- double px2, double py2) {
- return ((px1 - px0) * (py2 - py0) - (px2 - px0) * (py1 - py0));
- }
- public boolean isPointOnLine(double px0, double py0, double px1,
- double py1, double px2, double py2) {
- boolean flag = false;
- double ESP = 1e-9;
- if ((Math.abs(Multiply(px0, py0, px1, py1, px2, py2)) < ESP)
- && ((px0 - px1) * (px0 - px2) <= 0)
- && ((py0 - py1) * (py0 - py2) <= 0)) {
- flag = true;
- }
- return flag;
- }
- public boolean isIntersect(double px1, double py1, double px2, double py2,
- double px3, double py3, double px4, double py4) {
- boolean flag = false;
- double d = (px2 - px1) * (py4 - py3) - (py2 - py1) * (px4 - px3);
- if (d != 0) {
- double r = ((py1 - py3) * (px4 - px3) - (px1 - px3) * (py4 - py3))
- / d;
- double s = ((py1 - py3) * (px2 - px1) - (px1 - px3) * (py2 - py1))
- / d;
- if ((r >= 0) && (r <= 1) && (s >= 0) && (s <= 1)) {
- flag = true;
- }
- }
- return flag;
- }
- }